Adsorption of H on the Ge/Si(001) Surface as Studied by Time-of-Flight Elastic Recoil Detection Analysis and Coaxial Impact Collision Ion Scattering Spectroscopy

Abstract

We have used time-of-flight elastic recoil detection analysis (TOF-ERDA) and coaxial impact-collision ion scattering spectroscopy (CAICISS) to investigate the structural changes of the Ge/Si(100) surface caused by atomic hydrogen adsorption. The following conclusions have been reached. (1) When the Ge(1 ML)/Si(001) surface is exposed to atomic hydrogen at room temperature, the saturation coverage of hydrogen is slightly less than that for a clean Si(001) surface. (2) The desorption curve of hydrogen for this surface showed that the topmost layer of the surface is covered by about 0.45 ML of Ge atoms intermixed with Si atoms, and the rest of the 1 ML of Ge atoms are incorporated in the bulk Si layer. (3) Upon initial adsorption of hydrogen, the asymmetry of the Ge dimer is removed, forming the symmetric Ge dimer with a slightly expanded intradimer bond length.